Photographic process and compositions

ABSTRACT

PHOTOGRAPHIC COMPOSITIONS AND PROCESSES EMPLOYING A SILVER HALIDE DEVELOPER, AN AMINOALKANOL AND A MERCAPTO AZOLE ANTIFOGGANT.

United States Patent Office 3,576,633 Patented Apr. 27, 1971 3,576,633 PHOTOGRAPHIC PROCESS AND COMPOSITIONS Richard W. Henn and Bernadette D. Mack, Rochester,

N.Y1.\,I trgssignors to Eastman Kodak Company, Rochester, No Drawing. Filed June 27, 1967, Ser. No. 649,119 Int. Cl. G03c 5/30, 5 /50 U.S. Cl. 96-665 7 Claims ABSTRACT OF THE DISCLOSURE Photographic compositions and processes employing a silver halide developer, an aminoalkanol and amercapto azole antifoggant.

The present invention is directed to photographic processes and compositions. In a particular aspect, this invention relates to a reversal process employing a silver halide developing agent and an aminoalkanol with a mercapto azole antifoggant.

In another aspect, the invention is directed to a process for improved development in the first development step in a reversal process, especially a black-and-white reversal process.

It has been well known to develop positive photographic images by a conventional two-step negative-positive process. Another widely used procedure is the known reversal process in which the positive is obtained from an exposed silver halide emulsion in three main steps. The exposed silver halide emulsion is first developed to a negative image, then the silver formed during the first development step is bleached or converted to a light-insensitive silver salt which is water soluble. The remaining silver halide is then developed to a positive image in a second development step. The latter development step can be carried out in a developer without a re-exposure or in a developer following or during re-exposure.

While reversal processes are well known, they have been subject to certain shortcomings such as low contrast in the resulting image, loss in photographic speed, and relatively high minimum density.

It is, accordingly, an object of the present invention to provide a means for reversal processing of a silver halide emulsion which results in increased photographic speed and lower minimum density.

Another object of the invention is to provide an improved developer composition to decrease minimum density and provide increased speed of a photographic element.

These and other objects and advantages of the invention will be apparent from the following description.

The present invention comprises a photographic silver halide developer composition, particularly useful in reversal processing of a photographic element, comprising a silver halide developing agent, an aminoalkanol and a mercapto azole antifoggant.

It was completely unexpected to find that the use of this developer composition, especially in a reversal process, results in decreased minimum density as well as increased photographic speed and contrast of the element processed. Thus, in a developer solution the presence of a mercapto azole antifoggant generally produces a moderate increase in maximum density and gamma, but this is accompanied by a substantial loss in photographic speed. In contrast, when an aminoalkanol, as described herein, is present in the developer with the mercapto azole antifoggant, an unexpected increase in gamma and maximum density as well as an expected increase in photographic speed with a lowering of minimum density is achieved. The advantages of the combination are demonstrated in the following examples. Example 1 demonstrates that when one or both of the aminoalkanol and mercapto azole antifoggant are absent, the desired combination of increased gamma and maximum density without increased minimum density is not produced. Example 15 illustrates that neither an antifoggant, such as benzotriazole, containing no mercapto function or group, nor an antifoggant, such as thiosalicylic acid, containing no azole moiety provide the desired combination of results.

One embodiment of the invention comprises a photographic silver halide developer composition, especially an aqueous developer solution, suitable for reversal processing, comprising a silver halide developing agent, an aminoalkanol of the formula:

R2 R1N/ wherein R is a hydroxyalkyl radical, and R and R are each selected from the group consisting of hydrogen atoms and alkyl radicals; and a mercapto azole of the wherein Z represents the atoms necessary to complete a 5 or 6 membered heterocyclic ring and SX represents a mercapto function or group wherein X is a cation, including hydrogen, and n is a whole number from 1 to 3. A developer composition found especially suitable for reversal processing comprises an aqueous solution of a polyhydroxybenzene developing agent, l-amino-Z-propanol and 1-phenyl-S-mercaptotetrazole.

Another embodiment of the invention comprises, in a photographic process for developing a latent image in a photographic silver halide emulsion with a developer composition, the improvement of employing a developer composition containing a silver halide developing agent, an aminoalkanol and a mercapto azole antifoggant.

A preferred embodiment of the invention comprises, in a photographic reversal process for developing a latent image, the improvement comprising developing said latent image with a composition comprising a silver halide developing agent, an amino-alkanol and a mercapto azole antifoggant. According to this embodiment, a reversal process for developing a latent image in an exposed photographic silver halide emulsion is provided comprising developing an image in a developer composition comprising a silver halide developing agent, an aminoalkanol and a mercapto azole antifoggant, bleaching the resulting silver image and developing a positive image.

The emulsion after the first development step is typically re-exposed before subsequent processing or is re-exposed during the second development step. However, it is not necessary to carry out a re-exposure step after the first development step of a black-and-White reversal process if a so-called fogging developer is employed as the second developer composition. The use of the term fogging developer refers to a composition containing a component such as thiourea which sulfides the silver halide, or a developer containing strong reducing agents such as hydrazine or potassium borohydride.

Suitable aminoalkanols within the scope of the invention are those having at least one hydroxy alkyl radical and includes those compounds having one, two or more hydroxy radicals. These include compounds within the formula:

wherein R is a hydroxyalkyl radical such as one containing up to about 10 carbon atoms, typically a hydroxy lower alkyl radical, for example, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxyisobutyl, dihydroxypropyl, dihydroxybutyl and the like, which provide an amino lower alkanol, and R and R are each selected from the group consisting of hydrogen atoms and alkyl radicals, such as those containing up to about 10 carbon atoms, typically lower alkyl radicals, such as methyl, ethyl, propyl, butyl, isobutyl and isopropyl radicals.

Suitable aminoalkanols, which can be referred to as hydroxyalkyl amines, include:

1-amino-2-propanol 2-diethylaminoethanol 3-amino-l-propanol Z-amino-Z-methyl-l-propanol 3-diethylamino-l-propanol 3-di-n-butylamino-l-propanol 2-amino-2-mthyl-1,3-propanediol 3-dimethylamino-1,2-propanediol The mercapto azole antifoggants employed in the practice of this invention include those antifoggants which contain at least one mercapto function or group and at least one azole moiety. Suitable antifoggants can be represented wherein Z represents the atoms necessary to complete a 5 or 6 member heterocyclic ring, such as pyrimidine, triazine, tetrazole, triazole, imidazole, diazole, oxadiazole or thiadiazole ring; and SX represents a mercapto function, n being a whole number, typically a number from 1 to about 3, any free bonds being satisfied by hydrogen atoms. In mercapto function or group, X is a cation which includes hydrogen, an alkali metal, e.g., sodium or potassium, ammonium or an organic amine residue of such amines as triethyl amine, trietanol amine, morpholine and the like.

Mercapto tetrazole antifoggants are especially suitable in the practice of this invention and include those of the formula:

(III) NZN wherein R is an aliphatic or aromatic radical containing up to about 30 carbon atoms and SX is a mercapto function. As in structure H, X of the mercapto function or group is a cation including a hydrogen atom or, for example, an alkali metal such as sodium, potassium, ammonium or an organic amine residue of such amines as triethyl amine, triethanol amine, morpholine and the like. In addition, many of the mercapto tetrazoles within the scope of structure III can be in tautomeric form, for example, in the thione form, in which case the labile hydrogen atom in the mercapto function becomes bonded to the nitrogen atom and the group becomes a thiocarbonyl C=S) group. The term S-mercapto tetrazole, as employed herein, is intended to cover compounds in which the mercapto function is in any of these forms. R can be a hydrocarbon or nonhydrocarbon and includes alkyl or aryl radicals which can contain atoms or groups other than carbon and hydrogen. Suitable atoms or groups which can be present in R together with hydrogen and carbon include, for example, alkoxy, phenoxy, halogen, cyano, amino, substituted amino, sulfo, sulfamyl, substituted sulfamyl, sulfonylphenyl, sulfonylalkyl, fluosulfonyl, sulfonamidophenyl, sulfonamidoalkyl, carboxy, carboxylate, carbam- 4 yl, carbamylphenyl, carbamyalkyl, carbonylphenyl and similar groups.

Mercapto azole antifoggants within the scope of the invention include:

mercapto-substituted pyrimidines such as:

thiobarbituric acid and thiouracil, mercapto-substituted oxadiazoles or thiadiazoles such as:

S-phenyI-Z-mercapto-1,3,4-oxadiazole and 5-o-tolyl-2-mercapto-1,3,4-thiadiazole, mercapto triazines such as: 2,4,6-trimercapto-1,3,5-triazine, mercapto imidazoles such as: Z-mercapto-5-phenylimidazole, condensed imidazoles such as: Z-mercaptobenzimidazole, triazoles such as:

3,4,-diphenyl-5-mercapto-1,2,4-triazole and 3-mercapto-5-methyl-1,2,4-triazole, mercapto tetrazoles such as:

1-phenyl-5-mercaptotetrazole and 1- 3-capramido) phenyl-S-mercaptotetrazole.

Other compounds which are suitable are disclosed in Belgian Pat. 681,359.

Any of the silver halide developing agents can be employed in the practice of this invention. Suitable developing agents which can be employed are polyhydroxybenzenes, e.g., hydroquinone developing agents such as hydroquinone, alkyl substituted hydroquinones as exemplified by t butylhydroquinone, methylhydroquinone, dimethylhydroquinone; catechol and pyrogallol; chloro substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy substituted hydroquinones such as methoxy or ethoxy hydroquinone; aminophenol developing agents such as 2,4-diaminophenols and methylaminophenols; ascorbic acid; pyrazolidone developing agents such as 1-phenyl-3-pyrazolidone, including those described in British Pat. 930,572; and acyl derivatives of p-aminophenol such as disclosed in British Pat. 1,045,303. Such developing agents can be used alone or in combination.

Concentrations of the silver halide developing agent can vary over a wide range. Suitable concentrations in a developer composition will be determined based on other components, the desired image and other factors which can be determined by those skilled in the art. A typical concentration is about 2 to about 50 grams of developing agent per liter of processing solution.

The concentration of the aminoalkanol in solution is typically at least about 2 grams per liter up to about grams per liter of processing solution. Good results are often obtained with concentrations in the range of about 10 grams to about 50 grams per liter of processing solution.

The concentration of azole compound in solution is tyipcally in the range of about 0.02 gram per liter to about 0.5 gram per liter of solution.

The pH ranges which are suitable for the purposes of the invention can vary and include those typically employed in processing photographic elements. The pH is usually above about 7, for instance, about 10 to about 13.

Ordinary development activators can be employed with the above compositions and processes. These include the typical alkalis employed for activating developers, such as alkali metal hydroxides, typically sodium hydroxide, as well as other alkaline materials such as borax and alkali metal carbonates. These can be employed in any concentration which is effective for activating the development.

Various photographic addenda, particularly those known to be beneficial in photographic compositions, can be employed in the compositions of the invention as well as in the photographic elements processed. The types of addenda and concentrations to be employed can be determined by those skilled in the art. Suitable photographic addenda include, e.g., hardeners, such as alum or those set out in British Pat. 974,317; buffers which maintain the desired pH level including various sulfonamides and boraxes; coating aids; plasticizers; speed-increasing addenda, such as quaternary ammonium salts and alkylene oxide polymers such as polyethylene glycols; and stabilizing agents such as sodium sulfite.

The photographic emulsions employed in the practice of the invention can be sensitized using any of the wellknown techniques in emulsion making, for example, by digesting with naturally active gelatin or various sulfur, selenium, noble metal and/or gold compounds.

The photographic elements can also contain spectral sensitizing dyes such as described, for example, in U.S. Pats. 2,526,632 and 2,503,776. Spectral sensitizers which can be used include cyanines, merocyanines, styryls and hemicyanines.

The photographic elements processed according to the invention typically contain an emulsion layer comprising any of the known hydrophilic water permeable binding materials suitable for photographic purposes. These include, for example, gelatin, cellulose derivatives, polymerized vinyl compounds, water insoluble polymers of acrylates and methacrylates, as well as mixtures of such binding agents.

The photosensitive coatings which are processed according to the invention can be coated on a wide variety of supports. Typical supports include cellulose ester films, polyvinyl acetal films, polyethylene terephthalate films and related films and resinous materials as well as glass, paper, metals and the like. Paper supports which are coated with resinous materials such as polyethylene, polypropylene, ethylene-butene copolymers and the like can also be employed.

Various silver salts can be used as the sensitive salt in the elements processed according to the invention. These include silver halides such as silver iodide, silver bromide, silver chloride, silver bromoiodide, silver chloroiodide and the like.

Various silver halide fixing agents or solvents can also be employed in combination with the developer compositions and processes of the invention. These include alkali metal thiosulfates, such as sodium thiosulfate and thiocyanates such as ammonium thiocyanate.

The photographic elements processed according to the invention can typically be bleached or converted to a light insensitive silver salt which is water soluble following a first development step. Suitable compositions for carrying outer this bleaching are known and include potassium dichromate and sulfuric acid bleaching compositions.

The compositions of the invention containing the silver halide developer, aminoalkanol, and mercapto azole antifoggant can be employed in the first black-and-white development step in a color reversal process. Such color reversal processes usually comprise treating the exposed photographic element in a black-and-white development step, re-exposure of the element, a color development step, then bleaching and fixing the resulting image. A typical color reversal process is disclosed, for example, in U.S. Pat. 2,944,900.

It has been found that the addition of sucrose and/or other sugars to developer compositions has increased the stability of such compositions. For instance, sucrose and/or other sugars added to ascorbic acid developers, such as developers containing ascorbic acid with a 1 phenyl 3 pyrazolidone developing agent, greatly increases the stability of these developers. This is applicable especially to monobaths containing an alkaline material, ascorbic acid and a mercapto fixing agent, such as thioglycerol. Sucrose and/ or other sugars accordingly can be added to compositions of the present invention.

The temperatures which are normally employed in reversal processing are suitable for the purposes of the invention. Processing can be carried out at ambient temperatures such as between about 20 and about 30 C. or

at elevated temperatures such as those above about 50 C., e.g., about 50 C. to about C. Suitable temperatures can be determined by those skilled in the art.

The time of development with the compositions of the invention can vary between a second up to several minutes or more, depending on the desired image and processing conditions. The desired optimum time can be determined based on the element to be processed, temperatures of processing, various addenda present in the processing compositions and the like.

The components of the developer composition can be stored in individual containers, for instance in plastic packets or bottles as part of a kit, before processing is to be carried out. The silver halide developer, accordingly, can comprise a combination for use in an aqueous developer solution of a silver halide developing agent, an aminoalkanol and a mercapto azole antifoggant.

The invention is further illustrated in the following examples:

EXAMPLE 1 This example is a comparative example demonstrating reversal processing of a photographic element with (A) A developer composition containing a developing agent without an aminoalkanol and without an antifoggant,

(B) A developer composition with a developing agent and an aminoalkanol without an antifoggant,

(C) A developer composition with a developing agent and an antifoggant without an aminoalkanol, and

(D) A developer composition with a developing agent, an aminoalkanol and a mercapto azole antifoggant.

This example demonstrates that when either the aminoalkanol or the mercapto azole antifoggant are absent from the developer composition, the desired combination of increased gamma and maximum density without in creased minimum density, is not achieved.

A film containing a fine-grained, low speed silver bromoiodide gelatino photographic emulsion is exposed imagewise and divided into four equal strips, (A), (B), (C) and (D). Each part is processed at 55 C. for 5 seconds in three successive solutions with agitation. The first solution is a developer solution, the second a bleach solution and the third a fogging developer solution.

Strip (A) is treated in a first developer solution having the following composition:

Grams N-methyl-p-aminophenol 0.6 Sodium sulfite 50.0 Hydroquinone 20.0 Potassium bromide 8.0 Sodium hydroxide 20.0

Water to make 1 liter.

It is then treated in a bleach solution having the following composition:

Grams Potassium dichromate 25.0 Sulfuric acid (conc.) 31.0

Water to make 1 liter.

Finally, it is treated in a fogging developer solution having the following composition:

Grams Thiourea 20.0 Sodium hydroxide "a 5.0 Sodium sulfate 50.0

Water to make 1 liter.

Strip (D) is also treated in the same manner as strip (A) with the exception that 30 cc. of l-amino-Z-propanol and 0.1 gram of l-phenyl-5-mercaptotetrazole is added to each liter of the first developer solution.

The results obtained for each of these strips is given in Table I, the relative speed being calculated at 0.1 above fog level.

TABLE I Relative Contrast Strip speed (gamma) Dmin. DmBX.

(A) Control(no aminoalkanol or antiioggant).-. 100 1. 15 0. 20 1. 58 (B) l-amino-Z-propanol 480 0.75 0.11 0.78 (C) 1-phenyl-5-mercaptotetrazole 80 1. 64. 0. 17 1. 72 (D) l-amino-Z-propanol and 1-phenyl-fi-mercaptotetrazole 360 3.24 0.13 1.71

EXAMPLE 2 This example illustrates the use of l-amino-2-propanol at varying concentrations with 1-phenyl-5-mercaptotetrazole in reversal processing employing first and second developer solutions which are alike.

A film containing a fine-grained, low speed silver bromoiodide gelatino photographic emulsion is exposed imagewise to light. The resulting exposed emulsion is hand processed at 55 C. for 5 seconds in three successive solutions with agitation. The first solution is a developer solution having the following composition:

Grams Sodium sulfite 65.00 Sodium bromide 6.92 Phenylmercaptotetrazole 0.12 Dimezone 1.00 Hydroquinone 40.00

Water to make 1 liter. Potassium hydroxide added until solution has pH 12.3. The second solution is a bleach solution having the following composition:

Grams Potassium dichromate 25.0 Sulfuric acid (conc.) 32.0

Water to make 1 liter.

The third solution is a developer solution having the same composition as the first solution above. The emulsion is re-exposed by photoflood illumination during treatment in the third solution.

The procedure is repeated with the exception that l-amino 2 propanol is added at rates of 10, 30 and 50 cc. per liter to both the first and last solutions. After drying the resulting developed emulsions have the following values shown in Table II for relative speed, determined at a density of 0.1 above fog, contrast and minimum density.

TABLE II Concentration of 1-amino-2- Relaitve Contrast propanol speed (gamma) Dmin.

(control-no aminoalkanol) 100 1. 3 0. 42 10 cc. per liter 150 2. 1 0. 23 30 cc. per liter 280 2.6 0. 22 50 cc. per liter 1, 300 2. 3 0.26

EXAMPLE 3 This example illustrates the use of l-amino-Z-propanol at varying concentrations with l-phenyl 5 mercaptotetrazole in reversal processing employing a fogging developer as a second developer without an exposure step after the first developer A film containing a fine-grained, low speed silver bromoiodide gelatino photographic emulsion is exposed imagewise to light. The resulting exposed emulsion is hand processed at 55 C. for 5 seconds in three successive solutions with agitation as in Example 2 with the excep- 8 tion that the following solution is employed as the third solution:

Grams Thiourea 20.0 Sodium hydroxide 5.0 Sodium sulfate 50.0

Water to make 1 liter.

The procedure is repeated with the addition of l-amino- 2-propanol at the rates of 10, 30 and 50- cc. per liter of solution to the first developer solution. After drying, the resulting developed emulsions have the following values shown in Table III:

TABLE III Concentration of l-amino-Z- Relative Contrast propanol Speed (gamma) D... in

0 (control-n0 aminoalkanol) 1. 6 O. 15 10 cc. per liter 240 2. 9 0. 14 30 cc. per liter 630 5. 0 0. 14 50 00. per liter 1, 600 3. 8 0. 14

EXAMPLE 4 Grams Thiourea 20.0 Sodium hydroxide 5.0 Sodium sulfate 50.0

Water to make 1 liter.

The results are set out in Table IV in following Example 8. A control is also employed wherein no aminoalkanol is employed in either developer solution.

EXAMPLE 5 The procedure set out in Example 4 is repeated with the exception that 10 cc. per liter of solution of 3-aminol-propanol is added to the first developer solution in place of 2-diethylaminoethanol.

The results are set out in Table IV in following Example 8.

EXAMPLE 6 The procedure set out in Example 4 is repeated with the exception that 10 cc. per liter of solution of 2-amino- 2-methyl 1 propanol is added to the first developer solution in place of Z-diethylaminoethanol.

The results are set out in Table IV in following Example 8.

EXAMPLE 7 The procedure set out in Example 4 is repeated with the exception that 10 cc. per liter of solution of 3-diethylamino-l-propanol is added to the first developer solution in place of Z-diethylaminoethanol.

The results are set out in Table IV in following Example 8.

EXAMPLE 8 The procedure set out in Example 4 is repeated with the exception that 10 cc. per liter of solution of 3-di-nbutylamino-l-propanol is added to the first developer solution in place of Z-diethylaminoethanol. Only part of the 3-di-n-butylamino-l-propanol is soluble in the solution at this concentration.

The results are set out in Table IV.

The results shown in Table IV for 3-di-n-butylaminol-propanol demonstrate that it is desirable to employ an amount of aminoalkanol which is completely soluble in the developer solution used.

EXAMPLE 9 This example demonstrates the use of l-amino-Z-propanel and Z-thiouracil in reversal processing:

A film containing a fine-grained, low speed silver bromoiodide gelatino photographic emulsion is exposed imagewise. It is then processed for seconds in each of three successive processing solutions at 55 C. The first solution is a developer solution having the following composition:

l-amino-Z-propanol cc 30.1 N-methyl-p-aminophenol (Elon) grams 0.6 Sodium sulfite do 50.0 Hydroquinone do 20.0 Potassium bromide do 8.0 Sodium hydroxide ..do 20.0 2-Thiouracil do 0.1

Water to make 1 liter.

The second soluition is a bleach solution having the following composition:

10 EXAMPLE 10 The procedure set out in Example 9 is repeated with the exception that 0.1 gram per liter of solution of thiobarbituric acid of the formula /g: C H2 is employed in place of 2-thiouracil. The results are set out in Table V in following Example 13.

EXAMPLE 11 The procedure set out in Example 9 is repeated with the exception that 0.1 gram per liter of solution of 2-benzimidazole thiol of the formula:

I C-SH HC is employed in place of 2-thiouracil. The results are set out in Table V in following Example 13.

EXAMPLE 12 The procedure set out in Example 9 is repeated with the exception that 0.05 gram per liter of solution of S-phenyl-Z-mercapto-1,3,4-oxadiazole of the formula:

0 -o CSH is employed in place a 2-thiouracil. The results are set out in Table V in following Example 13.

EXAMPLE 13 The procedure set out in Example 9 is repeated with the exception that 0.05 gram per liter of solution of Potassium dichromate grams 25.0 1 phenyl 5 mercaptotetrazole is employed in place of Sulfuric acid (conc.) cc 32.0 2-thiourac1l. Water to make 1 liter. The results are set out in Table V.

TABLE V Relative Contrast Example Number speed (gamma) Dmin- D Contro1No aminoalkanol or mercaptoazole 100 0.95 0. 19 l. 69 Contro11-a1;nino-2-propanol without mercapto azole 650 1. 2 0. 15 1. 11 9. l-amino-Z-propanol with 2-thiouracil. 400 1. 4 0. 16 1. 36 10. 1-amino-2-propanol with thiobarbitur 380 1. 3 0. 15 1. 41 11. 1-amino-2-propanol with 2-benzlmidazole thiol. 250 1.25 0. l6 1. 44 12. 1-amino-2-propanol with 5-phenyl-2-mercapto- 1,3,4-oxadiazole 200 1. 0. 18 1. 92 13. l-amino-Z-propanol with 1-phenyl-5-mercaptotetrazole 320 1. 8 0. 18 1. 9

The third solution is a fogging developer having the following composition:

Grams Thiourea 20.0 Sodium hydroxide 5.0 Sodium sulfate 50.0

Water to make 1 liter.

A control is also employed in which no aminoalkanol or mercapto azole compounds are used in the developer solutions. A second control is employed in which l-amino- 2-propanol is used in the first developer solution in the absence of a mercapto azole compound.

The results are set out in Table V in following Example 13.

The results in Table V demonstrate that the presence of the mercapto azole compounds with the aminoalkanol provides increased maximum density of the developed image while maintaining the desired increased relative speed and contrast or gamma.

EXAMPLE 14 1 1 EXAMPLE 15 1-amino-2-propanol ml. 30.0 N-methyl-p-aminophenol (Elon) grams 0.6 Sodium sulfite 50.0 Hydroquinone do 20.0 Potassium bromide do 8.0 Sodium hydroxide d 20.0

Water to make 1 liter.

The second solution is a bleach solution having the following composition:

Potassium dichromate grams 25.0 Sulfuric acid (conc.) cc. 32.0 Water to make 1 liter.

The third solution is a fogging developer solution having the following composition:

Grams Thiourea 20.0 Sodium hydroxide 5.0 Sodium sulfate 50.0

Water to make 1 liter.

Strip (A) is treated with the addition of 0.1 gram of 1-phenyl-S-mercaptotetrazole to the first developer solution.

Strip (B) is treated in the same manner as strip (A) with the exception that 0.5 gram of thiosalicylic acid (a known mercapto antifoggant, but not a mercapto azole antifoggant) is added to the first developer solution in place of l-phenyl-S-mercaptotetrazole.

Strip (C) is treated in the same manner as strip (A) with the exception that 5 grams of benzotriazole (a known azole antifoggant, not containing a mercapto group) is added to the first developer solution in place of 1-phenyl-5-mercaptotetrazole.

The results obtained for each of the strips is set out in Table VI, the relative speed being calculated at 0.1

The results in Table VI demonstrate that only strip (A) which was treated in a first developer solution containing l-amino-Z-propanol and l-phenyl-S-mercaptotetrazole provides the desired combination of relative speed, increased gamma, and increased maximum density.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected without departing from the spirit and scope of the invention as described herein above and as defined in the appended claims.

We claim:

1. A reversal process for developing a latent image in an exposed photographic silver halide emulsion compri ing developing said latent image with a composition comprising a silver halide developing agent, an amino lower alkanol and a mercapto azole antifoggant; bleaching the resulting silver image; and developing a positive image in said emulsion.

2. A process as in claim 1 wherein said aminoalkanol is an aminoalkanol of the formula:

RiN

formula:

( Z sx).

wherein Z represents the atoms necessary to complete a 5 or 6 member heterocyclic ring, and SX represents a mercapto function wherein X is a cation and n is a whole number from 1 to about 3.

3. A process as in claim 1 wherein said aminoalkanol is l-amino-2-propanol.

4. A process as in claim 1 wherein said mercapto azole is 1-phenyl-S-mercaptotetrazole.

5. A process as in claim 1 wherein said developing of a positive image, after said bleaching, is carried out with a composition which comprises a silver halide developing agent, an aminoalkanol and a mercapto azole antifoggant.

6. A process as in claim 1 also comprising carrying out said developing at temperatures above about 50 C.

7. A reversal process for developing a latent image in an exposed photographic silver halide emulsion comprising developing said latent image in an aqueous solution comprising a hydroquinone developing agent, about 30 cc. per liter of said solution of l-amino-2-propanol and about 0.02 gram to about 0.5 gram per liter of said solution of 1-phenyl-S-mercaptotetrazole at a temperature above about 50 C.; bleaching the resulting image; and developnig a positive image in said emulsion.

References Cited UNITED STATES PATENTS 3,335,009 8/1967 Rasch et a1. 9661 3,232,761 2/1966 Allen et al. 96-66 NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, Assistant Examiner U.S. Cl. X.R. 96-59 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3 576,633 Dated April 2'? 1971 Inventor(s) Richard W. Henn and Bernadette D. Mack It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 3 line 19 (page 5, line 12 of the application) "2-amino-2-mthyl-l,3-propanediol" should read 2-amino2methyll,3propanediol In column 3, line 39 (page 5, line 28 of the application) "trietanol" should read --triethanol--.

In column LL, line 56 (page 8, line 19 of the application), "tyipcally" should read ---typically---.

In column 6, line 58 (page 13, line 17 of the application), "31.0" should read 32.0--

In column 8, line 20 (page 16, line 19 of the application) "2.9" should read --l.9--.

In column 9, line 3L4. (page 19, line 6 of the application) "30.1" should read -30.0--.

In column 12, line 52 (last line of claim 16 in the application) "developnig" should read --developing- Signed and sealed this 16th day of November 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents 

